The number of patients undergoing treatment to open blocked, or stenosed arteries is continually increasing. There are various surgical methods to reopen the arteries, such as balloon angioplasty and rotational arthrectomy. However, practicing these methods may result in injuries to internal arterial walls which predispose the artery to scarring and restenosis. For example, about fifty percent of arteries opened with balloon angioplasty will scar to the point of restenosis.
Expensive chemical and genetic interventions to resurface internal vascular walls which have been damaged during surgery are known. Such chemical and genetic interventions methods involve both high cost and the introduction of exogenous agents which increase the risk of adverse reaction in the patient.
A less costly alternative to chemical or genetic interventions involves the use of endovascular stents. An endovascular stent is a tubular support structure which fits within the lumen of a blood vessel at a site of damage and supports the walls of the artery in their normal open configuration. The use of such stents however, is complicated by scarring around the stent from the site of damage. In addition to causing restenosis of the vessel, this scarring also may become a stimulus for thrombogenesis.
Grafting is a process in which healthy tissue is used to replace damaged tissue and reduce or eliminate scarring. The process of grafting may include taking viable tissue from an undamaged donor site on the patient herself (autograft), from another person (homograft), from another species (heterograft), using tissue which has been artificially grown or engineered, and using tissue which has been cryogenically frozen. Grafting has the general advantage that damaged tissue can literally be replaced by healthy tissue which incorporates itself with the existing healthy tissue surrounding the damaged site. The end result of a successful graft is complete tissue restoration at the injury site and reduction of scarring.
It would be desirable to provide apparatus and methods which reduce scarring and prevent restenosis in a damaged blood vessel, but which avoid the use of costly pharmaceutical agents or genetic interventions. It would further be desirable to provide apparatus and methods which employ stents in combination with grafts to support and resurface internal blood vessel walls and prevent restenosis due to scarring after vascular surgery.